Author

Date of Award

Document Type

Degree Name

Department

Graduate Studies

Committee Chair

Dr. Daewon Kim

First Committee Member

Dr. Sirish Namilae

Second Committee Member

Dr. Dongeun Seo

Third Committee Member

Dr. Feng Zhu

Abstract

A solid mechanical spring generally exhibits uniform stiffness. This thesis studies a mechanical spring filled with magnetorheological (MR) fluid to achieve controllable stiffness. The hollow spring filled with MR fluid is subjected to a controlled magnetic field in order to change the viscosity of the MR fluid and thereby to change the overall stiffness of the spring. MR fluid is considered as a Bingham viscoplastic linear material in the mathematical model. The goal of this research is to study the feasibility of such spring system by analytically and numerically computing the effects of MR fluid on the overall spring stiffness. For this purpose, spring mechanics and MR fluid behavior are studied to increase the accuracy of the analytical analysis. Numerical simulations are also performed to generate some assumptions, which simplify calculations in the analytical part of the analysis. The accuracy of the present analytical approach is validated by comparing the results to previously known experimental results. Overall stiffness variations of the spring, calculated through the developed equations, are also discussed for different spring designs. Simulation of a helical hollow spring with an annular cross section filled with MR fluid is performed using ANSYS by means of two-way Fluid-Structural Interaction (FSI). The simulation shows that MR fluid effect is capable of controlling the stiffness of the spring in some ranges.